There is an increasing desire for a lighting system that can be controlled, i.e. for which the emitted lighting pattern can be changed dynamically or can be selected according to need.
A particular application for such a lighting system is in automotive headlights. For example, it may be desirable in a first state for the automotive headlight to have a high beam pattern but omitting a section to avoid illuminating an oncoming vehicle to avoid glare. Alternatively, there may be a desire to adapt the direction of illumination for example to illuminate road signs, curves in the road, obstacles or other features.
There are a number of different approaches to realising dynamic adaptation of lighting, including for example switchable mechanical apertures, LED matrix lights, microdisplays, or laser scanners.
In one laser scanner approach, a laser beam is used to illuminate a micromirror which directs the laser beam onto a phosphor acting as a converter. The converter may be used to convert light of one wavelength, for example blue, to another wavelength or spread of wavelengths to generate suitable colours. A lens may then be used to project the light onto the road. By moving the micromirror, a range of patterns can be produced.
However, a problem that occurs is that the range of motion of the micromirror is restricted. This can make it difficult to generate some desired patterns. Also, the restricted range of motion of the micromirror results in the need for a large distance between micromirror and phosphor, but this makes the optical design more difficult.